Low bouncing at hot idle

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RobFour1Four

New Member
Low bouncing idle HOT OUTSIDE

Heres a video i took of my problem. I revved it in the beginning to start the bounce because it settled down. but usually if its really hot out, it keeps doing it.

YouTube - Low bouncing idle when hot honda

It doesnt seem to be the iacv because i unplugged it and it turned off my car almost instantly. so that means its working right?

I checked for vacuum leaks but I couldnt find any, and my boost gauge is reading -20 consistent.

I thought it was my tune, but it did this on stock basemap with stock injectors.
 
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no i didnt check them. but its a boosted b18c1. but it also did it when it was n/a for break in. so idk what the problem is. how do i check tps voltage and what range should it be
 
Does the TPS have screw heads or do they "look" like they're riveted on there?
Use a multimeter and on the TPS...green is the ground and red is the power that fluctuates by TB blade
Roughly .45v with TB closed and around 5.0v at WOT (key to on position and motor off)

Try to turn the idle adjsut screw on TB to the right (righty tighty) slowly and see if it does anything. Its made mine stop before but who knows for you. I am not a turbo guy but if it was doing it N/A....it shouldn't be turbo related.
 
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I had that problem with my teg.. only because of using an obd1 vc on an obd2 intake.. ive also had friends cars do that when there egr valve was going bad or was bad.. especially the 2nd gen eclipses
 
so i just checked my tps. and wot is close to 5v. about 4.7-4.9v and closed is at about 4. something isnt right, right? the tps bad?
 
Rivets....just means its a factory USDM TPS on the throttle body...if it truly needs to be adjusted or changed...we'll cross that bridge is we need to.

At closed throttle....it was.....???? It should be 0.5v....so less then one look for the decimal point to make sure
 
Hmmmm....and you were on green for ground and red for power? Just don't want to send you down the wrong path.

If these are your readings....this could be your problem. I'm gonna look in my Helm Manual (B18C1) and see what it says
 
A good experiment would be to try a known working TB (maybe you have one or know a friend who can let you borrow it)

Otherwise....you can purchase a TPS sensor (I think Blox makes one but don't quote me).
Then take your TB off.
Use a dremel or file to make flat head grooves in the rivet "looking" screws that hold the TPS to the TB.
Make grooves so a flat head screw driver you have will fit in there and back those two screws out.
TPS will come off then (just a side note....JDM TB versions have those "star" head screws so they're easier to replace).
Now you can replace the TPS.
Install the new one and go through the same voltage tests to "clock" the TPS in a position that satisfies both closed and WOT voltage readings
....and tighten new bolts down (or you can technically use the olds ones you made with a dremel)

This MAY be the fix but....like I said earlier.....I would like to see you troubleshoot with a spare complete TB b/c its just easier and less costly
 
okay, i havent checked if it was the tps. i got a holley fpr and got rid of my fmu. the car runs fine on warm and cooler weather.. today was finally a hotter and more humid weather and found some problems. the car did this again.. it would take awhile, but i figured it out. the car runs fine when its at full operating temp, but when the weather is hotter (80f and up) the engine does this bounce.. but it doesnt seem to die. any answers would be great. kind of narrowed it down more
 
Silly stuff like coolant level? You Burped/Bled it after putting the new motor in? (your description read like it was a rebuilt B18C1)

Maybe get a colder thermostat?? (opens up at a lower temperature)

Is it doing it when the fan turns on?

Do you have Power Steering? If so....does it do it when you turn the wheels?

Also....do you have a Fast Idle Thermo Valve (FITV)? If so....you can check it pretty easy and I'll tell you how if you need me to.

When you put the P72 ECU in....you Didn't get any codes at all? That seems odd to me b/c you don't have the secondary butterflies in the IM (b/c of the Skunk IM) and I figure that would be at least one code you should see (although easily fixed with a chipped...preferably socketed ECU)

Check Engine Light Bulb is still good? You see the light come on when the key is in the 'on' position before you start it?

SORRY....I got a lot of weird questions.....just trying to help you a little.
 
no i appreciate the help GREATLY! ha but yes the cel light is fine and it is a chipped ecu. i cant say forsure that there are no cels because all the sensors were disabled in crome on the tune but when i had stock basemap everything was enabled and there was no cel and its still the same. how would i "burp" the coolant? and maybe is i swapped thermos with my old block is may fix the issue. power steering is a no and i dont have a fitv. how would i burp the coolant and maybe ill do that swapping of the thermostat
 
Burp/Bleed the coolant system simply by taking the radiator cap off and get the car up to running temp (thermo opens up). Obviously give it some water (if it will take any) while it warms up. If it needs to be Burped/Bled.....when the thermo opens up, it will want more water/coolant (you'll see the level go down through the radiator cap hole). Give it some more water and you should be good to go. Or you can wait and see if it wants more water. The procedure does take a few minutes but its pretty easy. It might fix things

Also....I know you need the tuned ECU but for diagnosis....try using a VIRGIN P72 ECU and see if you get any codes.....I think it might be helpful.

Or...have you tried a different IACV???
 
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